The oxidizing agents present in blonding agents are capable of lightening the hair fiber by oxidatively destroying melanin, the hair's own pigment. For a moderate blonding effect, it is sufficient to use only hydrogen peroxide—optionally with the use of ammonia or other alkalizing agents—as the oxidizing agent; to achieve a stronger blonding effect, a mixture of hydrogen peroxide and peroxodisulfate salts and/or peroxomonosulfate salts is typically used.
For stability reasons, commercially available blonding agents are customarily offered in two preparations that are packaged separately from each other and mixed immediately before use to form a completely mixed application preparation. Commercially available blonding agents are usually composed of a liquid oxidizing agent preparation and a powder that contains solid oxidizing agents. As an alternative, it is possible to mix pasty agents with a liquid oxidizing agent preparation instead of the powder, whereby the dusting problem during production and mixing is avoided. Products comprising additional components are likewise offered commercially.
Pasty blonding agents generally contain larger amounts of an inert oil, which may result in stability problems (separation of the solid oxidizing agent from the oil). However, a concentration gradient may occur within the packaging even if peroxydisulfates have not fully settled, so that differing portions from the packaging may effectuate varying lightening after mixing. So as to minimize these problems, a high viscosity is desirable.
On the other hand, the viscosity of the blonding paste must be low enough for the paste to be easily and quickly mixed with the liquid oxidizing agent preparation. The resulting blonding mixture moreover must be sufficiently liquid so as to be applied easily and evenly, yet viscous enough so as not to drip off the head or application aids, such as brushes. In addition, the resulting blonding mixture should also not separate since consumers perceive settling or phase separation as a quality defect.
WO 2009/134875 A1 describes blonding agents containing persulfate salts and an oil gel, which, in turn, is composed of oil(s) and certain polymers.
According to this invention, stability against settling and phase separation are described as desirable properties of the agent.
EP 1 034 777 A1 discloses agents for lightening keratinic fibers, comprising at least two preparations (A) and (B) packaged separately from each other, which are mixed immediately before use to form an application mixture, wherein preparations (A) are oil-based and contain polymer(s) that form oleogels or lipogels.
It was the object of the present invention to further improve the properties of blonding agents, the goal being in particular to increase storage stability, wherein not only the physical stability (settling, phase separation), but also the chemical stability (decomposition of the persalts) were to be improved.
It has been shown that higher oil-containing blonding pastes thickened with specific polymers are particularly stable when the persulfates satisfy certain criteria.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.